The Clearwater System is believed to be the largest interconnected cave system in the world by volume.
The main cave system of Mulu and the 7th longest cave in the world at 268.68km (12/2025), the system lies mainly under the western margins of Gunung Api between the Melinau Gorge and Lagangs Cave.
Total Length: 268,689m
Vertical Range: 553.41m
Component Caves:
Clearwater – discovered 1978
Lady’s Cave – connected 1978
Cleartop Cave – connected 1978
Wind Cave – connected 1988
Drunken Forest Cave – connected 1990
Blackrock Cave – connected 1991
Leopard Cave – connected 1994
Whiterock Cave – connected 2005
Racer/Easter Caves – connected 2022
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Discovered in 1978, Clearwater Cave was the first major component of the system, itself explored to 51km length over several expeditions between 1978 to 1984. In 1988 a small expedition connected Cave of the Winds to Clearwater and discovered the 24km long Blackrock Cave, which in 1991 was connected with Clearwater. A further 15km of passage was also added to Clearwater Cave itself in that same year
But the big move had to wait another 12 years until 2003 when Whiterock Cave was discovered to the north of Blackrock. Initially it was expected the new find would quickly join with Blackrock and, although it indeed did, Whiterock also ran wild into the mountain extending to 101km length over eight further expeditions in 2005, 2007, 2009, 2011, 2013, 2015, 2017, 2018 and 2019. Whiterock Cave now forms the largest component of the Clearwater system at 108km.
With the connection of additional caves such as Drunken Forest (in 1990), Leopard (in 1984) and Racer/Easter (in 2022), the total length of the Clearwater System at present (October 2024) is 258.55km, with likely much more to come.
From south to north the Clearwater Cave System measures 10.8km. Its southernmost entrance is Cave of the Winds, and northernmost is Whiterock Cave’s lower entrance.
